This adds a new optional file to the root of elements. The
file lists dependencies which will be added to the list
requested by the user during disk image creation.
Change-Id: Id71c3b333563604bbbaf90f9cf40e24fa9738fc8
Flavour is overloaded in openstack due to it being used by nova. Element
seems to have the same feeling of combinability without using a term already
in active use in the openstack community.
Change-Id: Ia4c028d4062a8f69c66665821c94dd4bcdf06031
